I plan to study the effect of thymic polypeptides on human T cell differentiation in vitro in normals, patients with congenital immunodeficiency diseases and patients with systemic lupus erythematosus. Peripheral blood mononuclear cells from normals, immunodeficient patients and systemic lupus erythematosus patients separated on a Ficoll-Hypaque density gradient and bone marrow cells from normals and immunodeficient patients fractionated on Ficoll-Hypaque and BSA gradients are incubated with thymic polypeptides (thymosin alpha 1, alpha 5, alpha 7) or control reagents (media, BSA, calf spleen fraction 5). Following exposure to the various reagents, the ability of these cells to display functional T cell responses (i.e., mitogen and alloantigen reactivity; T killer, helper and suppressor activity) and T cell markers will be studied. This research may help define specific pathways of human T cell differentiation and may suggest useful therapeutic approaches in patients with congenital immunodeficiency and autoimmune diseases associated with suppressor T cell abnormalities.